Prospective, randomized, multi-centered clinical trial assessing safety and efficacy of a synthetic cartilage implant versus first metatarsophalangeal arthrodesis in advanced hallux rigidus

J. Baumhauer, D. Singh, M. Glazebrook, C. Blundell, G. Wansbrough, G. de Vries, I. Le, D. Nielson, E. Petersen, A. Sakellariou, M. Solan, A. Younger, T. Daniels, M.O.T.I.O.N. Research Team

¹URMC Rochester, Rochester, United States

²Royal National Orthopaedic Hospital, Foot and Ankle Unit, Stanmore, United Kingdom

³QE II Health Sciences Centre, Halifax, Canada

⁴Northern General Hospital, Sheffield, United Kingdom

⁵Torbay Hospital, Torbay, United Kingdom

⁶Everett Chalmers Hospital, Fredericton, Canada

⁷Calgary General Hospital, Calgary, Canada

⁸St Geoge's Hospital, London, United Kingdom

⁹University of WarwickAlberta, Edmonton, Canada

¹⁰Frimley Park Hospital, Frimley, United Kingdom

¹¹Royal Surrey County Hospital, Guildford, United Kingdom

¹²St Geoge's HospitalPaul's Hospital, Vancouver, Canada

¹³St Geoge's HospitalMichael's Hospital, Toronto, Canada 

Methods: Patients with advanced stage hallux rigidus from 12 centers in Canada and the UK were randomized (2:1) to treatment with a small (8/10 mm) hydrogel implant (Cartiva) or 1^st MTP arthrodesis. VAS pain scale, validated outcome measures (FAAM sport scale), great toe active dorsiflexion motion, secondary procedures, radiographic assessment and safety parameters were evaluated.
236 patients were initially enrolled, 17 patients withdrew prior to randomization, 17 patients withdrew after randomization and 22 were non-randomized training patients, leaving 152 implant and 50 arthrodesis patients. Standard demographics and baseline outcomes were similar for both groups.

Results: Mean VAS pain scores decreased from 6.8 and 6.9 respectively for the implant and arthrodesis groups from baseline to 1.4 and 0.7 at 24 months. Similarly, the FAAM sports score improved significantly from baseline levels of 37 and 36 to 24 months level of 77 and 82 respectively for the implant and arthrodesis groups. First MTP active dorsiflexion motion improved an average of 4° at 3 months after implant placement and was maintained at 24 months. Secondary surgeries occurred in 17 (11.2%) implant patients and 6 (12.0%) arthrodesis patients. Fourteen (9.2%) implants were removed and converted to arthrodesis and 6 (12.0%) arthrodesis patients had painful hardware requiring removal. There was no case of implant fragmentation, wear, or bone loss. Analysis of a single composite endpoint utilizing the three primary study outcomes (pain, function, and safety) showed statistical equivalence between the  two groups.

Conclusion: In patients requiring surgery for advanced stage hallux rigidus, treatment with a small synthetic cartilage implant resulted in comparable clinically important pain relief and functional outcomes compared to 1^st MTP arthrodesis while preserving and often improving great toe motion. Secondary surgical intervention was similar in the implant and arthrodesis groups. Revision from a small implant plug to arthrodesis can be performed if needed.

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